Journal articles: 'GCAPs'

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Ames, James B. "Structural Insights into Retinal Guanylate Cyclase Activator Proteins (GCAPs)." International Journal of Molecular Sciences 22, no. 16 (August 13, 2021): 8731. http://dx.doi.org/10.3390/ijms22168731.

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Retinal guanylate cyclases (RetGCs) promote the Ca2+-dependent synthesis of cGMP that coordinates the recovery phase of visual phototransduction in retinal rods and cones. The Ca2+-sensitive activation of RetGCs is controlled by a family of photoreceptor Ca2+ binding proteins known as guanylate cyclase activator proteins (GCAPs). The Mg2+-bound/Ca2+-free GCAPs bind to RetGCs and activate cGMP synthesis (cyclase activity) at low cytosolic Ca2+ levels in light-activated photoreceptors. By contrast, Ca2+-bound GCAPs bind to RetGCs and inactivate cyclase activity at high cytosolic Ca2+ levels found in dark-adapted photoreceptors. Mutations in both RetGCs and GCAPs that disrupt the Ca2+-dependent cyclase activity are genetically linked to various retinal diseases known as cone-rod dystrophies. In this review, I will provide an overview of the known atomic-level structures of various GCAP proteins to understand how protein dimerization and Ca2+-dependent conformational changes in GCAPs control the cyclase activity of RetGCs. This review will also summarize recent structural studies on a GCAP homolog from zebrafish (GCAP5) that binds to Fe2+ and may serve as a Fe2+ sensor in photoreceptors. The GCAP structures reveal an exposed hydrophobic surface that controls both GCAP1 dimerization and RetGC binding. This exposed site could be targeted by therapeutics designed to inhibit the GCAP1 disease mutants, which may serve to mitigate the onset of retinal cone-rod dystrophies.

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Imanishi, Yoshikazu, Lili Yang, Izabela Sokal, S?awomir Filipek, Krzysztof Palczewski, and Wolfgang Baehr. "Diversity of Guanylate Cyclase-Activating Proteins (GCAPs) in Teleost Fish: Characterization of Three Novel GCAPs (GCAP4, GCAP5, GCAP7) from Zebrafish (Danio rerio) and Prediction of Eight GCAPs (GCAP1-8) in Pufferfish (Fugu rubripes)." Journal of Molecular Evolution 59, no. 2 (August 2004): 204–17. http://dx.doi.org/10.1007/s00239-004-2614-y.

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Gorczyca, Wojciech A., Marcin Kobiałka, Marianna Kuropatwa, and Ewa Kurowska. "Ca2+ differently affects hydrophobic properties of guanylyl cyclase-activating proteins (GCAPs) and recoverin." Acta Biochimica Polonica 50, no. 2 (June 30, 2003): 367–76. http://dx.doi.org/10.18388/abp.2003_3691.

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Guanylyl cyclase-activating proteins (GCAPs) and recoverin are retina-specific Ca(2+)-binding proteins involved in phototransduction. We provide here evidence that in spite of structural similarities GCAPs and recoverin differently change their overall hydrophobic properties in response to Ca(2+). Using native bovine GCAP1, GCAP2 and recoverin we show that: i) the Ca(2+)-dependent binding of recoverin to Phenyl-Sepharose is distinct from such interactions of GCAPs; ii) fluorescence intensity of 1-anilinonaphthalene-8-sulfonate (ANS) is markedly higher at high [Ca(2+)](free) (10 microM) than at low [Ca(2+)](free) (10 nM) in the presence of recoverin, while an opposing effect is observed in the presence of GCAPs; iii) fluorescence resonance energy transfer from tryptophane residues to ANS is more efficient at high [Ca(2+)](free) in recoverin and at low [Ca(2+)](free) in GCAP2. Such different changes of hydrophobicity evoked by Ca(2+) appear to be the precondition for possible mechanisms by which GCAPs and recoverin control the activities of their target enzymes.

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Dejda, Agnieszka, Izabela Matczak, and Wojciech A. Gorczyca. "p19 detected in the rat retina and pineal gland is a guanylyl cyclase-activating protein (GCAP)." Acta Biochimica Polonica 49, no. 4 (December 31, 2002): 899–905. http://dx.doi.org/10.18388/abp.2002_3749.

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The Ca(2+)-dependent activation of retina-specific guanylyl cyclase (retGC) is mediated by guanylyl cyclase-activating proteins (GCAPs). Here we report for the first time detection of a 19 kDa protein (p19) with GCAP properties in extracts of rat retina and pineal gland. Both extracts stimulate synthesis of cGMP in rod outer segment (ROS) membranes at low (30 nM) but not at high (1 microM) concentrations of Ca(2+). At low Ca(2+), immunoaffinity purified p19 activates guanylyl cyclase(s) in bovine ROS and rat retinal membranes. Moreover, p19 is recognized by antibodies against bovine GCAP1 and, similarly to other GCAPs, exhibits a Ca(2+)-dependent electrophoretic mobility shift.

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Vinberg, Frans, Teemu T. Turunen, Hanna Heikkinen, Marja Pitkänen, and Ari Koskelainen. "A novel Ca2+-feedback mechanism extends the operating range of mammalian rods to brighter light." Journal of General Physiology 146, no. 4 (September 28, 2015): 307–21. http://dx.doi.org/10.1085/jgp.201511412.

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Sensory cells adjust their sensitivity to incoming signals, such as odor or light, in response to changes in background stimulation, thereby extending the range over which they operate. For instance, rod photoreceptors are extremely sensitive in darkness, so that they are able to detect individual photons, but remain responsive to visual stimuli under conditions of bright ambient light, which would be expected to saturate their response given the high gain of the rod transduction cascade in darkness. These photoreceptors regulate their sensitivity to light rapidly and reversibly in response to changes in ambient illumination, thereby avoiding saturation. Calcium ions (Ca2+) play a major role in mediating the rapid, subsecond adaptation to light, and the Ca2+-binding proteins GCAP1 and GCAP2 (or guanylyl cyclase–activating proteins [GCAPs]) have been identified as important mediators of the photoreceptor response to changes in intracellular Ca2+. However, mouse rods lacking both GCAP1 and GCAP2 (GCAP−/−) still show substantial light adaptation. Here, we determined the Ca2+ dependency of this residual light adaptation and, by combining pharmacological, genetic, and electrophysiological tools, showed that an unknown Ca2+-dependent mechanism contributes to light adaptation in GCAP−/− mouse rods. We found that mimicking the light-induced decrease in intracellular [Ca2+] accelerated recovery of the response to visual stimuli and caused a fourfold decrease of sensitivity in GCAP−/− rods. About half of this Ca2+-dependent regulation of sensitivity could be attributed to the recoverin-mediated pathway, whereas half of it was caused by the unknown mechanism. Furthermore, our data demonstrate that the feedback mechanisms regulating the sensitivity of mammalian rods on the second and subsecond time scales are all Ca2+ dependent and that, unlike salamander rods, Ca2+-independent background-induced acceleration of flash response kinetics is rather weak in mouse rods.

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Peshenko, Igor V., Elena V. Olshevskaya, and Alexander M. Dizhoor. "GUCY2D mutations in retinal guanylyl cyclase 1 provide biochemical reasons for dominant cone–rod dystrophy but not for stationary night blindness." Journal of Biological Chemistry 295, no. 52 (October 27, 2020): 18301–15. http://dx.doi.org/10.1074/jbc.ra120.015553.

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Mutations in the GUCY2D gene coding for the dimeric human retinal membrane guanylyl cyclase (RetGC) isozyme RetGC1 cause various forms of blindness, ranging from rod dysfunction to rod and cone degeneration. We tested how the mutations causing recessive congenital stationary night blindness (CSNB), recessive Leber's congenital amaurosis (LCA1), and dominant cone–rod dystrophy-6 (CORD6) affected RetGC1 activity and regulation by RetGC-activating proteins (GCAPs) and retinal degeneration-3 protein (RD3). CSNB mutations R666W, R761W, and L911F, as well as LCA1 mutations R768W and G982VfsX39, disabled RetGC1 activation by human GCAP1, -2, and -3. The R666W and R761W substitutions compromised binding of GCAP1 with RetGC1 in HEK293 cells. In contrast, G982VfsX39 and L911F RetGC1 retained the ability to bind GCAP1 in cyto but failed to effectively bind RD3. R768W RetGC1 did not bind either GCAP1 or RD3. The co-expression of GUCY2D allelic combinations linked to CSNB did not restore RetGC1 activity in vitro. The CORD6 mutation R838S in the RetGC1 dimerization domain strongly dominated the Ca2+ sensitivity of cyclase regulation by GCAP1 in RetGC1 heterodimer produced by co-expression of WT and the R838S subunits. It required higher Ca2+ concentrations to decelerate GCAP-activated RetGC1 heterodimer—6-fold higher than WT and 2-fold higher than the Ser838-harboring homodimer. The heterodimer was also more resistant than homodimers to inhibition by RD3. The observed biochemical changes can explain the dominant CORD6 blindness and recessive LCA1 blindness, both of which affect rods and cones, but they cannot explain the selective loss of rod function in recessive CSNB.

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Neuman, L. M., M. Van Nieuwland, M. Vermeer, D. Boumans, E. Colin, and C. Alves. "AB0375 EXTERNAL VALIDATION OF THE GIANT CELL ARTERITIS PROBABILITY SCORE IN THE NETHERLANDS." Annals of the Rheumatic Diseases 80, Suppl 1 (May 19, 2021): 1214–15. http://dx.doi.org/10.1136/annrheumdis-2021-eular.2466.

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Background:Severe complications of giant cell arteritis (GCA), such as blindness and ischemic stroke, can be prevented by timely treatment. This requires early and accurate diagnosis. In 2019, Laskou et al. developed a clinical GCA probability score (GCAPS) that allows physicians to assess the probability of GCA at initial assessment. The GCAPS is suitable for easy implementation in daily practice. It has a high sensitivity (95.7%) and specificity (86.7%) at a cut-off value of 9.5 as proposed by Laskou et al.Objectives:The aim of this study was to externally validate the GCAPS in a general hospital.Methods:A retrospective cohort of patients with suspected GCA between January 1st 2017 and October 1st 2019 at Ziekenhuisgroep Twente (the Netherlands) was used. As the parameter extra-cranial artery abnormality was not available in our cohort, a modified version of the GCAPS was used (m-GCAPS). The m-GCAPS was compared to clinical diagnosis of a rheumatologist after six months in accordance with Laskou et al. The validity of the m-GCAPS was assessed by plotting a receiver operating characteristic (ROC) curve and assessing sensitivity and specificity for multiple cut-off values. For practical purposes, risk stratifications as proposed by Sebastian et al. (2020) were applied to our data (low-risk <9; intermediate-risk 9-12; high-risk >12).Results:In our cohort, 40 GCA patients and 95 controls (suspected of GCA) had complete records and were therefore used for analysis. In the patient group, 29 (72.5%) were female and mean (SD) age was 73.3 (1.6). The area under the ROC curve (AUC) was 0.83 (95% CI 0.75 – 0.91). At our optimal cut-off value of 10.5, sensitivity was 80.0% and specificity was 75.8%. In total, 5 patients and 45 controls were stratified as low, 7 patients and 35 controls as intermediate and 28 patients and 15 controls as high-risk.Conclusion:The m-GCAPS showed good discrimination in our cohort. Risk stratification of patients looks promising, although cut-off values by Sebastian et al. might need optimization based on population and modification to the GCAPS. Colour Doppler ultrasound is recommended by EULAR as the first-choice diagnostic test to confirm GCA in case of high pre-test probability and exclude GCA for low pre-test probability. The (m-)GCAPS may aid in quantification of this pre-test probability.References:[1]Laskou F, Coath F, Mackie SL et al. A probability score to aid the diagnosis of suspected giant cell arteritis. Clin Exp Rheumatol. 2019;37 Suppl 1(2):104–8.[2]Sebastian A, Tomelleri A, Kayani A et al. Probability-based algorithm using ultrasound and additional tests for suspected GCA in a fast-track clinic. RMD Open. 2020 Sep 1;6(3):e001297.[3]Dejaco C, Ramiro S, Duftner C et al. EULAR recommendations for the use of imaging in large vessel vasculitis in clinical practice. Ann Rheum Dis. 2018 May 1;77(5):636 LP – 643.Table 1.Cut-off values of the m-GCAPS stratified into risk categories as proposed by Sebastian et al. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) and the number of patients scoring above or below the cut-off values are described (optimal cut-off value in blue). The total number of patients with a score within low- (red), intermediate- (orange) and high- (green) risk categories are depicted.GCA+ (N)N=40GCA- (N)N=95Scorem-GCAPSGCA+ (N)GCA- (N)Sens. (%)Spec. (%)PPV (%)NPV (%)Low-risk <95 (12.5%)45 (47.4%)5.5<5.501410014.733.1100>5.540818.5<8.554587.547.441.290>8.53550Intermediate-risk9-127 (17.5%)35 (36.8%)9.5<9.58568058.945.187.5>9.5323910.5<10.58728075.858.290>10.5322311.5<11.510747577.958.888.1>11.53021High-risk>928 (70.0%)15 (15.8%)12.5<12.512807084.265.187>12.5281514.5<14.518895593.778.683.2>14.522619.5<19.537957.510010072>19.530Figure 1.ROC curve depicting sensitivity and (1-) specificity. The AUC was 0.83 (95.0% CI 0.75-0.91) with an optimal cut-off value of 10.5 (sensitivity 80.0%, specificity 75.8%).Disclosure of Interests:None declared

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Ingram, Norianne T., Alapakkam P. Sampath, and Gordon L. Fain. "Voltage-clamp recordings of light responses from wild-type and mutant mouse cone photoreceptors." Journal of General Physiology 151, no. 11 (September 27, 2019): 1287–99. http://dx.doi.org/10.1085/jgp.201912419.

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We describe the first extensive study of voltage-clamp current responses of cone photoreceptors in unlabeled, dark-adapted mouse retina using only the position and appearance of cone somata as a guide. Identification was confirmed from morphology after dye filling. Photocurrents recorded from wild-type mouse cones were biphasic with a fast cone component and a slower rod component. The rod component could be eliminated with dim background light and was not present in mouse lines lacking the rod transducin-α subunit (Gnat1−/−) or connexin 36 (Cx36−/−). Cones from Gnat1−/− or Cx36−/− mice had resting membrane potentials between −45 and −55 mV, peak photocurrents of 20–25 picoamps (pA) at a membrane potential Vm = −50 mV, sensitivities 60–70 times smaller than rods, and a total membrane capacitance two to four times greater than rods. The rate of activation (amplification constant) was largely independent of the brightness of the flash and was 1–2 s−2, less than half that of rods. The role of Ca2+-dependent transduction modulation was investigated by recording from cones in mice lacking rod transducin (Gnat1), recoverin, and/or the guanylyl-cyclase–activating proteins (GCAPs). In confirmation of previous results, responses of Gnat1−/−;Gcaps−/− cones and triple-mutant Gnat1−/−;Gcaps−/−;Rv−/− cones recovered more slowly both to light flashes and steps and were more sensitive than cones expressing the GCAPs. Cones from all four mouse lines showed significant recovery and escaped saturation even in bright background light. This recovery occurred too rapidly to be caused by pigment bleaching or metaII decay and appears to reflect some modulation of response inactivation in addition to those produced by recoverin and the GCAPs. Our experiments now make possible a more detailed understanding of the cellular physiology of mammalian cone photoreceptors and the role of conductances in the inner and outer segment in producing cone light responses.

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Baehr, Wolfgang, and Krzysztof Palczewski. "Focus on Molecules: Guanylate cyclase-activating proteins (GCAPs)." Experimental Eye Research 89, no. 1 (June 2009): 2–3. http://dx.doi.org/10.1016/j.exer.2008.12.016.

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Peshenko, Igor V., and Alexander M. Dizhoor. "Guanylyl Cyclase-activating Proteins (GCAPs) Are Ca2+/Mg2+Sensors." Journal of Biological Chemistry 279, no. 17 (March 1, 2004): 16903–6. http://dx.doi.org/10.1074/jbc.c400065200.

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Avesani, Anna, Laura Bielefeld, Nicole Weisschuh, Valerio Marino, Pascale Mazzola, Katarina Stingl, Tobias B. Haack, Karl-Wilhelm Koch, and Daniele Dell’Orco. "Molecular Properties of Human Guanylate Cyclase-Activating Protein 3 (GCAP3) and Its Possible Association with Retinitis Pigmentosa." International Journal of Molecular Sciences 23, no. 6 (March 17, 2022): 3240. http://dx.doi.org/10.3390/ijms23063240.

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The cone-specific guanylate cyclase-activating protein 3 (GCAP3), encoded by the GUCA1C gene, has been shown to regulate the enzymatic activity of membrane-bound guanylate cyclases (GCs) in bovine and teleost fish photoreceptors, to an extent comparable to that of the paralog protein GCAP1. To date, the molecular mechanisms underlying GCAP3 function remain largely unexplored. In this work, we report a thorough characterization of the biochemical and biophysical properties of human GCAP3, moreover, we identified an isolated case of retinitis pigmentosa, in which a patient carried the c.301G>C mutation in GUCA1C, resulting in the substitution of a highly conserved aspartate residue by a histidine (p.(D101H)). We found that myristoylated GCAP3 can activate GC1 with a similar Ca2+-dependent profile, but significantly less efficiently than GCAP1. The non-myristoylated form did not induce appreciable regulation of GC1, nor did the p.D101H variant. GCAP3 forms dimers under physiological conditions, but at odds with its paralogs, it tends to form temperature-dependent aggregates driven by hydrophobic interactions. The peculiar properties of GCAP3 were confirmed by 2 ms molecular dynamics simulations, which for the p.D101H variant highlighted a very high structural flexibility and a clear tendency to lose the binding of a Ca2+ ion to EF3. Overall, our data show that GCAP3 has unusual biochemical properties, which make the protein significantly different from GCAP1 and GCAP2. Moreover, the newly identified point mutation resulting in a substantially unfunctional protein could trigger retinitis pigmentosa through a currently unknown mechanism.

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Dizhoor, Alexander M., Elena V. Olshevskaya, and Igor V. Peshenko. "Regulation Of Photoreceptor Guanylyl Cyclase By Ca2+/Mg2+ Exchange In GCAPs." Biophysical Journal 96, no. 3 (February 2009): 199a. http://dx.doi.org/10.1016/j.bpj.2008.12.1071.

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Sokal, Izabela, Andrei Alekseev, and Krzysztof Palczewski. "Photoreceptor guanylate cyclase variants: cGMP production under control." Acta Biochimica Polonica 50, no. 4 (December 31, 2003): 1075–95. http://dx.doi.org/10.18388/abp.2003_3633.

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Changes in the Ca2+ concentration are thought to affect many processes, including signal transduction in a vast number of biological systems. However, only in few cases the molecular mechanisms by which Ca2+ mediates its action are as well understood as in phototransduction. In dark-adapted photoreceptor cells, the equilibrium level of cGMP is maintained by two opposing activities, such as phosphodiesterase (PDE) and guanylate cyclase (GC). Upon absorption of photons, rhodopsin-G-protein-mediated activation of PDE leads to a transient decrease in [cGMP] and subsequently to lowering of [Ca2+]. In turn, lower [Ca2+] increases net production of cGMP by stimulation of GC until dark conditions are re-established. This activation of GC is mediated by Ca2+ -free forms of Ca2+ -binding proteins termed GC-activating proteins (GCAPs). The last decade brought the molecular identification of GCs and GCAPs in the visual system. Recent efforts have been directed toward understanding the properties of GC at the physiological and structural levels. Here, we summarize the recent progress and present a list of topics of ongoing research.

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Pennesi, M. E., K. A. Howes, W. Baehr, and S. M. Wu. "Guanylate cyclase-activating protein (GCAP) 1 rescues cone recovery kinetics in GCAP1/GCAP2 knockout mice." Proceedings of the National Academy of Sciences 100, no. 11 (May 5, 2003): 6783–88. http://dx.doi.org/10.1073/pnas.1130102100.

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Lamb, Trevor D., and David M. Hunt. "Evolution of the calcium feedback steps of vertebrate phototransduction." Open Biology 8, no. 9 (September 2018): 180119. http://dx.doi.org/10.1098/rsob.180119.

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We examined the genes encoding the proteins that mediate the Ca-feedback regulatory system in vertebrate rod and cone phototransduction. These proteins comprise four families: recoverin/visinin, the guanylyl cyclase activating proteins (GCAPs), the guanylyl cyclases (GCs) and the sodium/calcium-potassium exchangers (NCKXs). We identified a paralogon containing at least 36 phototransduction genes from at least fourteen families, including all four of the families involved in the Ca-feedback loop (recoverin/visinin, GCAPs, GCs and NCKXs). By combining analyses of gene synteny with analyses of the molecular phylogeny for each of these four families of genes for Ca-feedback regulation, we have established the likely pattern of gene duplications and losses underlying the expansion of isoforms, both before and during the two rounds of whole-genome duplication (2R WGD) that occurred in early vertebrate evolution. Furthermore, by combining our results with earlier evidence on the timing of duplication of the visual G-protein receptor kinase genes, we propose that specialization of proto-vertebrate photoreceptor cells for operation at high and low light intensities preceded the emergence of rhodopsin, which occurred during 2R WGD.

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Howes, K. A. "GCAP1 rescues rod photoreceptor response in GCAP1/GCAP2 knockout mice." EMBO Journal 21, no. 7 (April 1, 2002): 1545–54. http://dx.doi.org/10.1093/emboj/21.7.1545.

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Codega, Paolo, Luca Della Santina, Claudia Gargini, Diana E. Bedolla, Tatiana Subkhankulova, Frederick J. Livesey, Luigi Cervetto, and Vincent Torre. "Prolonged Illumination Up-regulates Arrestin And Two GCAPs: A Novel Mechanism For Light Adaptation." Biophysical Journal 96, no. 3 (February 2009): 525a—526a. http://dx.doi.org/10.1016/j.bpj.2008.12.2712.

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Mendez, A., M. E. Burns, I. Sokal, A. M. Dizhoor, W. Baehr, K. Palczewski, D. A. Baylor, and J. Chen. "Role of guanylate cyclase-activating proteins (GCAPs) in setting the flash sensitivity of rod photoreceptors." Proceedings of the National Academy of Sciences 98, no. 17 (August 7, 2001): 9948–53. http://dx.doi.org/10.1073/pnas.171308998.

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Tucker, Chandra L., Richard P. Laura, and James B. Hurley. "Domain-Specific Stabilization of Photoreceptor Membrane Guanylyl Cyclase by Adenine Nucleotides and Guanylyl Cyclase Activating Proteins (GCAPs)†." Biochemistry 36, no. 39 (September 1997): 11995–2000. http://dx.doi.org/10.1021/bi971212k.

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Dizhoor, Alexander M., and Igor V. Peshenko. "Regulation of retinal membrane guanylyl cyclase (RetGC) by negative calcium feedback and RD3 protein." Pflügers Archiv - European Journal of Physiology 473, no. 9 (February 3, 2021): 1393–410. http://dx.doi.org/10.1007/s00424-021-02523-4.

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AbstractThis article presents a brief overview of the main biochemical and cellular processes involved in regulation of cyclic GMP production in photoreceptors. The main focus is on how the fluctuations of free calcium concentrations in photoreceptors between light and dark regulate the activity of retinal membrane guanylyl cyclase (RetGC) via calcium sensor proteins. The emphasis of the review is on the structure of RetGC and guanylyl cyclase activating proteins (GCAPs) in relation to their functional role in photoreceptors and congenital diseases of photoreceptors. In addition to that, the structure and function of retinal degeneration-3 protein (RD3), which regulates RetGC in a calcium-independent manner, is discussed in detail in connections with its role in photoreceptor biology and inherited retinal blindness.

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Peshenko, Igor V., Elena V. Olshevskaya, and Alexander M. Dizhoor. "Evaluating the Role of Retinal Membrane Guanylyl Cyclase 1 (RetGC1) Domains in Binding Guanylyl Cyclase-activating Proteins (GCAPs)." Journal of Biological Chemistry 290, no. 11 (January 23, 2015): 6913–24. http://dx.doi.org/10.1074/jbc.m114.629642.

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Dizhoor, Alexander M., Elena V. Olshevskaya, and Igor V. Peshenko. "Mg2+/Ca2+ cation binding cycle of guanylyl cyclase activating proteins (GCAPs): role in regulation of photoreceptor guanylyl cyclase." Molecular and Cellular Biochemistry 334, no. 1-2 (December 2, 2009): 117–24. http://dx.doi.org/10.1007/s11010-009-0328-6.

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McKeown, Alex S., and Timothy W. Kraft. "Adaptive potentiation in rod photoreceptors after light exposure." Journal of General Physiology 143, no. 6 (May 12, 2014): 733–43. http://dx.doi.org/10.1085/jgp.201411163.

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Photoreceptors adapt to changes in illumination by altering transduction kinetics and sensitivity, thereby extending their working range. We describe a previously unknown form of rod photoreceptor adaptation in wild-type (WT) mice that manifests as a potentiation of the light response after periods of conditioning light exposure. We characterize the stimulus conditions that evoke this graded hypersensitivity and examine the molecular mechanisms of adaptation underlying the phenomenon. After exposure to periods of saturating illumination, rods show a 10–35% increase in circulating dark current, an adaptive potentiation (AP) to light exposure. This potentiation grows as exposure to light is extended up to 3 min and decreases with longer exposures. Cells return to their initial dark-adapted sensitivity with a time constant of recovery of ∼7 s. Halving the extracellular Mg concentration prolongs the adaptation, increasing the time constant of recovery to 13.3 s, but does not affect the magnitude of potentiation. In rods lacking guanylate cyclase activating proteins 1 and 2 (GCAP−/−), AP is more than doubled compared with WT rods, and halving the extracellular Mg concentration does not affect the recovery time constant. Rods from a mouse expressing cyclic nucleotide–gated channels incapable of binding calmodulin also showed a marked increase in the amplitude of AP. Application of an insulin-like growth factor-1 receptor (IGF-1R) kinase inhibitor (Tyrphostin AG1024) blocked AP, whereas application of an insulin receptor kinase inhibitor (HNMPA(AM)3) failed to do so. A broad-acting tyrosine phosphatase inhibitor (orthovanadate) also blocked AP. Our findings identify a unique form of adaptation in photoreceptors, so that they show transient hypersensitivity to light, and are consistent with a model in which light history, acting via the IGF-1R, can increase the sensitivity of rod photoreceptors, whereas the photocurrent overshoot is regulated by Ca-calmodulin and Ca2+/Mg2+-sensitive GCAPs.

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Yue, Wendy W. S., Daniel Silverman, Xiaozhi Ren, Rikard Frederiksen, Kazumi Sakai, Takahiro Yamashita, Yoshinori Shichida, M. Carter Cornwall, Jeannie Chen, and King-Wai Yau. "Elementary response triggered by transducin in retinal rods." Proceedings of the National Academy of Sciences 116, no. 11 (February 22, 2019): 5144–53. http://dx.doi.org/10.1073/pnas.1817781116.

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G protein-coupled receptor (GPCR) signaling is crucial for many physiological processes. A signature of such pathways is high amplification, a concept originating from retinal rod phototransduction, whereby one photoactivated rhodopsin molecule (Rho*) was long reported to activate several hundred transducins (GT*s), each then activating a cGMP-phosphodiesterase catalytic subunit (GT*·PDE*). This high gain at the Rho*-to-GT* step has been challenged more recently, but estimates remain dispersed and rely on some nonintact rod measurements. With two independent approaches, one with an extremely inefficient mutant rhodopsin and the other with WT bleached rhodopsin, which has exceedingly weak constitutive activity in darkness, we obtained an estimate for the electrical effect from a single GT*·PDE* molecular complex in intact mouse rods. Comparing the single-GT*·PDE* effect to the WT single-photon response, both in Gcaps−/− background, gives an effective gain of only ∼12–14 GT*·PDE*s produced per Rho*. Our findings have finally dispelled the entrenched concept of very high gain at the receptor-to-G protein/effector step in GPCR systems.

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Stephen, Ricardo, Krzysztof Palczewski, and Marcelo C. Sousa. "The Crystal Structure of GCAP3 Suggests Molecular Mechanism of GCAP-linked Cone Dystrophies." Journal of Molecular Biology 359, no. 2 (June 2006): 266–75. http://dx.doi.org/10.1016/j.jmb.2006.03.042.

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Semple-Rowland, Susan L., Wojciech A. Gorczyca, Janina Buczylko, Bharati S. Helekar, Claudia C. Ruiz, Iswari Subbaraya, Krzysztof Palczewski, and Wolfgang Baehr. "Expression of GCAP 1 and GCAP2 in the retinal degeneration (rd ) mutant chicken retina." FEBS Letters 385, no. 1-2 (April 29, 1996): 47–52. http://dx.doi.org/10.1016/0014-5793(96)00345-6.

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Payne, Annette M., Susan M. Downes, David A. R. Bessant, Catherine Plant, Tony Moore, Alan C. Bird, and Shomi S. Bhattacharya. "Genetic analysis of the guanylate cyclase activator 1B (GUCA1B) gene in patients with autosomal dominant retinal dystrophies: Table 1." Journal of Medical Genetics 36, no. 9 (September 1, 1999): 691–93. http://dx.doi.org/10.1136/jmg.36.9.691.

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The guanylate cyclase activator proteins (GCAP1 and GCAP2) are calcium binding proteins which by activating Ret-GC1 play a key role in the recovery phase of phototransduction. Recently a mutation in theGUCA1A gene (coding for GCAP1) mapping to the 6p21.1 region was described as causing cone dystrophy in a British family. In addition mutations in Ret-GC1have been shown to cause Leber congenital amaurosis and cone-rod dystrophy. To determine whether GCAP2 is involved in dominant retinal degenerative diseases, the GCAP2 gene was screened in 400 unrelated subjects with autosomal dominant central and peripheral retinal dystrophies.A number of changes involving the intronic as well as the coding sequence were observed. In exon 1 a T to C nucleotide change was observed leaving the tyrosine residue 57 unchanged. In exon 3 a 1 bp intronic insertion, a single nucleotide substitution G to A in the intron 3′ of this exon, and a GAG to GAT change at codon 155 were observed. This latter change results in a conservative change of glutamic acid to aspartic acid. In exon 4 a 7 bp intronic insertion, a single nucleotide A to G substitution in the intron 5′ of this exon, and a single base pair change C to G in the intron 3′ of exon 4 were seen. None of these changes would be expected to affect correct splicing of this gene. All these changes were observed in controls. The results of this study do not show any evidence so far that GCAP2 is involved in the pathogenesis of autosomal dominant retinal degeneration in this group of patients. All the changes detected were found to be sequence variations or polymorphisms and not disease causing.

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Roth, Nora, Christoph Faul, Christiane Dorn, Wichard Vogel, Wolfgang A. Bethge, Lothar Kanz, Hans-Georg Rammensee, and Sebastian P. Haen. "Development of New Autoimmunity Against T Cell Antigens Derived From Retinal Proteins After Allogeneic Hematopoietic Cell Transplantation." Blood 120, no. 21 (November 16, 2012): 3060. http://dx.doi.org/10.1182/blood.v120.21.3060.3060.

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Abstract Abstract 3060 Introduction: Graft versus host disease (GvHD) is mainly mediated by T cells recognizing major (MHC) and minor (miHAG) histocompatibility antigens (human leukocyte antigens and MHC-restricted epitopes, respectively). The clinical appearance of a GvHD affecting the central nervous system (CNS) and the retina as part of the CNS is rare and evidence is limited to single case reports. Some publications describe the development of new autoimmunity after hematopoietic cell transplantation (HCT) manifested as hemolytic anemia (AIHA), immune thrombocytopenia (ITP) or myasthenia gravis. Of note, new autoinflammatory diseases affecting the retina have not been reported. In this study we investigated the GvHD of the retina and examined the development of new autoimmune T cell responses against epitopes derived from proteins exclusively expressed in the retina. Patients and Methods: We analyzed T cells from 8 women and 12 men with a median age of 55 years (range 29 – 69 years) that had underwent HCT. Underlying diseases were acute lymphoblastic leukemia (n = 1), acute myeloid leukemia, (n = 6), chronic myeloid leukemia (n = 1), myelodysplastic syndrome (n = 3), myeloproliferative syndromes (primary myelofibrosis, n = 2; essential thrombocytemia with secondary myelofibrosis, n = 2; polycythemia vera with secondary myelofibrosis, n = 1), B-cell non-Hodgkin lymphoma (gray zone lymphoma, n = 1; follicular lymphoma, n = 1; peripheral T cell lymphoma, n = 1) and Hodgkin's lymphoma (n = 1). Potential T cell epitopes from four unique highly polymorphic retinal proteins (membrane-bound retinal guanylate cyclase 1 protein (retGC), the guanylate cyclase activating proteins 1 and 2 (GCAP1 and GCAP2) and the retinoid binding protein 3 (RBP3)) were identified using 2 approaches. First, genomic DNA derived from both donor and recipient coding for these proteins was sequenced by Sanger sequencing in search of single nucleotide polymorphisms (SNP). Second, alternate peptide expression based on known SNP was predicted using internet based databases (EpiToolKit). The predicted epitopes were synthesized and used in T cell assays. Peripheral blood mononuclear cells (PBMCs) from patients after hematopoietic regeneration (neutrophils > 500/μl) were stimulated with SNP peptide pairs (peptides pairs differing in one amino acid) and analyzed by IFNg-ELISPOT and flow cytometry. Results: In 5 out of 20 patients (25%), strong T cell responses against peptides derived from retGC as well as from GCAP1 and GCAP2 were observed which were not detectable before HCT and not reflected by a difference in the DNA sequence between donor and recipient. Two patients of the cohort presented with visual loss which was due to cone dystrophy (n = 1) and retrobulbar optic neuritis (n = 1). In the patient with cone dystrophy, we observed circulating antigen specific T cells against peptides derived from retGC. The patient with retrobulbar optic neuritis did not have antigen specific T cell responses. In 2 clinically silent patients, we found IFNg producing CD4+ T cells that recognized a predicted GCAP1-derived self-peptide. One patient also had a strong T cell response against a GCAP2-derived self-peptide. The T cells specifically recognized the peptide represented in the autologous DNA sequence; no reactivity was seen after stimulation with the SNP peptide. Furthermore, the T cell reactions persisted over time and were still detectable one year after HCT. In another patient, T cell responses against the pair of GCAP2 peptides were detected. Here, the reactivity against one peptide could not be discriminated due to limited availability of patient T cells. One further patient displayed T cell responses against GCAP and retGC peptides, which were directed against both self- and SNP peptides. As controls we stimulated T cells from 5 HLA-matched healthy individuals with all respective peptides and observed no T cell reaction. Conclusions: 25% of the patients revealed strong T cell responses against retinal autoantigens after HCT. T cell responses detected late after HCT as observed in 3 patients might indicate a chronic antigen exposure. Clinical manifestations were cone dystrophy (here, antigen-specific T cells against cone protein-derived peptides could be detected) and retrobulbar optic neuritis. To our knowledge, this is the first report on antigen-specificity of neoautoinflammatory cells after allogeneic HCT. Disclosures: No relevant conflicts of interest to declare.

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Wilkie, Susan E., Inez Stinton, Phillippa Cottrill, Evelyne Deery, Richard Newbold, Martin J. Warren, Shomi S. Bhattacharya, and David M. Hunt. "Characterisation of two genes for guanylate cyclase activator protein (GCAP1 and GCAP2) in the Japanese pufferfish, Fugu rubripes." Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression 1577, no. 1 (August 2002): 73–80. http://dx.doi.org/10.1016/s0167-4781(02)00413-x.

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Surguchov, Andrei, J. Darin Bronson, Poulabi Banerjee, James A. Knowles, Claudia Ruiz, Iswari Subbaraya, Krzysztof Palczewski, and Wolfgang Baehr. "The Human GCAP1 and GCAP2 Genes Are Arranged in a Tail-to-Tail Array on the Short Arm of Chromosome 6 (p21.1)." Genomics 39, no. 3 (February 1997): 312–22. http://dx.doi.org/10.1006/geno.1996.4513.

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Peshenko, Igor V., Gennadiy P. Moiseyev, Elena V. Olshevskaya, and Alexander M. Dizhoor. "Factors that Determine Ca2+Sensitivity of Photoreceptor Guanylyl Cyclase. Kinetic Analysis of the Interaction between the Ca2+-Bound and the Ca2+-Free Guanylyl Cyclase Activating Proteins (GCAPs) and Recombinant Photoreceptor Guanylyl Cyclase 1 (RetGC-1)†." Biochemistry 43, no. 43 (November 2004): 13796–804. http://dx.doi.org/10.1021/bi048943m.

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Bondarenko, Vladimir A., Fumio Hayashi, Jiro Usukura, and Akio Yamazaki. "Involvement of rhodopsin and ATP in the activation of membranous guanylate cyclase in retinal photoreceptor outer segments (ROS-GC) by GC-activating proteins (GCAPs): a new model for ROS-GC activation and its link to retinal diseases." Molecular and Cellular Biochemistry 334, no. 1-2 (November 26, 2009): 125–39. http://dx.doi.org/10.1007/s11010-009-0323-y.

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Gallego, Iván, Alicia Rioboo, José J. Reina, Bernardo Díaz, Ángeles Canales, F. Javier Cañada, Jorge Guerra‐Varela, Laura Sánchez, and Javier Montenegro. "Glycosylated Cell‐Penetrating Peptides (GCPPs)." ChemBioChem 20, no. 11 (April 12, 2019): 1400–1409. http://dx.doi.org/10.1002/cbic.201800720.

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Kim, Kyung Hwan. "International Harmonization of GCPs." Journal of Korean Society for Clinical Pharmacology and Therapeutics 4, no. 1 (1996): 54. http://dx.doi.org/10.12793/jkscpt.1996.4.1.54.

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Rosenberg, MaryEllen. "Implementing GCPs in Asia." Quality Assurance Journal 4, no. 2 (2000): 73–77. http://dx.doi.org/10.1002/1099-1786(200006)4:2<73::aid-qaj101>3.0.co;2-c.

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Vladimirov, Vasiliy I., Viktoriia E. Baksheeva, Irina V. Mikhailova, Ramis G. Ismailov, Ekaterina A. Litus, Natalia K. Tikhomirova, Aliya A. Nazipova, Sergei E. Permyakov, Evgeni Yu Zernii, and Dmitry V. Zinchenko. "A Novel Approach to Bacterial Expression and Purification of Myristoylated Forms of Neuronal Calcium Sensor Proteins." Biomolecules 10, no. 7 (July 10, 2020): 1025. http://dx.doi.org/10.3390/biom10071025.

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N-terminal myristoylation is a common co-and post-translational modification of numerous eukaryotic and viral proteins, which affects their interaction with lipids and partner proteins, thereby modulating various cellular processes. Among those are neuronal calcium sensor (NCS) proteins, mediating transduction of calcium signals in a wide range of regulatory cascades, including reception, neurotransmission, neuronal growth and survival. The details of NCSs functioning are of special interest due to their involvement in the progression of ophthalmological and neurodegenerative diseases and their role in cancer. The well-established procedures for preparation of native-like myristoylated forms of recombinant NCSs via their bacterial co-expression with N-myristoyl transferase from Saccharomyces cerevisiae often yield a mixture of the myristoylated and non-myristoylated forms. Here, we report a novel approach to preparation of several NCSs, including recoverin, GCAP1, GCAP2, neurocalcin δ and NCS-1, ensuring their nearly complete N-myristoylation. The optimized bacterial expression and myristoylation of the NCSs is followed by a set of procedures for separation of their myristoylated and non-myristoylated forms using a combination of hydrophobic interaction chromatography steps. We demonstrate that the refolded and further purified myristoylated NCS-1 maintains its Ca2+-binding ability and stability of tertiary structure. The developed approach is generally suited for preparation of other myristoylated proteins.

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Feng, Nancy Chun. "Economic Consequences of Going Concern Audit Opinions in Nonprofit Charitable Organizations." Journal of Governmental & Nonprofit Accounting 3, no. 1 (December 1, 2013): 20–34. http://dx.doi.org/10.2308/ogna-50676.

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ABSTRACT This study examines the economic consequences of going concern audit reports (GCARs) in nonprofit charitable organizations (NPOs) using a sample of public charities that received initial GCARs between 1998 and 2003. I find that GCARs are negatively correlated with subsequent government grants. This evidence suggests either that the government utilizes GCARs as a screening criterion in its funding decisions or that affected NPOs voluntarily withdraw their grant applications. GCARs and subsequent contributions are also negatively correlated. There is no evidence of a significant correlation between a GCAR and the NPO's subsequent public support. The findings indicate detectable adverse economic consequences of GCARs in the nonprofit sector. Data Availability: Data used in this study are from public sources.

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Yao, Z., Y. Du, Y. Tao, X. Zheng, C. Liu, S. Lin, and K. Butterbach-Bahl. "Water-saving ground cover rice production system reduces net greenhouse gas fluxes in an annual rice-based cropping system." Biogeosciences 11, no. 22 (November 17, 2014): 6221–36. http://dx.doi.org/10.5194/bg-11-6221-2014.

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Abstract. To safeguard food security and preserve precious water resources, the technology of water-saving ground cover rice production system (GCRPS) is being increasingly adopted for rice cultivation. However, changes in soil water status and temperature under GCRPS may affect soil biogeochemical processes that control the biosphere–atmosphere exchanges of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2). The overall goal of this study is to better understand how net ecosystem greenhouse gas exchanges (NEGE) and grain yields are affected by GCRPS in an annual rice-based cropping system. Our evaluation was based on measurements of the CH4 and N2O fluxes and soil heterotrophic respiration (CO2 emissions) over a complete year, and the estimated soil carbon sequestration intensity for six different fertilizer treatments for conventional paddy and GCRPS. The fertilizer treatments included urea application and no N fertilization for both conventional paddy (CUN and CNN) and GCRPS (GUN and GNN), and solely chicken manure (GCM) and combined urea and chicken manure applications (GUM) for GCRPS. Averaging across all the fertilizer treatments, GCRPS increased annual N2O emission and grain yield by 40 and 9%, respectively, and decreased annual CH4 emission by 69%, while GCRPS did not affect soil CO2 emissions relative to the conventional paddy. The annual direct emission factors of N2O were 4.01, 0.09 and 0.50% for GUN, GCM and GUM, respectively, and 1.52% for the conventional paddy (CUN). The annual soil carbon sequestration intensity under GCRPS was estimated to be an average of −1.33 Mg C ha−1 yr−1, which is approximately 44% higher than the conventional paddy. The annual NEGE were 10.80–11.02 Mg CO2-eq ha−1 yr−1 for the conventional paddy and 3.05–9.37 Mg CO2-eq ha−1 yr−1 for the GCRPS, suggesting the potential feasibility of GCRPS in reducing net greenhouse effects from rice cultivation. Using organic fertilizers for GCRPS considerably reduced annual emissions of CH4 and N2O and increased soil carbon sequestration, resulting in the lowest NEGE (3.05–5.00 Mg CO2-eq ha−1 yr−1). Accordingly, water-saving GCRPS with organic fertilizer amendments was considered the most promising management regime for simultaneously achieving relatively high grain yield and reduced net greenhouse gas emission.

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Yao, Z., Y. Du, Y. Tao, X. Zheng, C. Liu, S. Lin, and K. Butterbach-Bahl. "Water-saving ground cover rice production system reduces net greenhouse gas fluxes in an annual rice-based cropping system." Biogeosciences Discussions 11, no. 6 (June 13, 2014): 8925–67. http://dx.doi.org/10.5194/bgd-11-8925-2014.

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Abstract. To safeguard food security and preserve precious water resources, the technology of water-saving ground cover rice production system (GCRPS) is being increasingly adopted for the rice cultivation. However, changes in soil water status and temperature under GCRPS may affect soil biogeochemical processes that control the biosphere–atmosphere exchanges of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2). The overall goal of this study is to better understand how net ecosystem greenhouse gas exchanges (NEGE) and grain yields are affected by GCRPS in an annual rice-based cropping system. Our evaluation was based on measurements of the CH4 and N2O fluxes and soil heterotrophic respiration (CO2 emission) over a complete year, as well as the estimated soil carbon sequestration intensity for six different fertilizer treatments for conventional paddy and GCRPS. The fertilizer treatments included urea application and no N fertilization for both conventional paddy (CUN and CNN) and GCRPS (GUN and GNN), solely chicken manure (GCM) and combined urea and chicken manure applications (GUM) for GCRPS. Averaging across all the fertilizer treatments, GCRPS increased annual N2O emission and grain yield by 40% and 9%, respectively, and decreased annual CH4 emission by 69%, while GCRPS did not affect soil CO2 emissions relative to the conventional paddy. The annual direct emission factors of N2O were 4.01, 0.087 and 0.50% for GUN, GCM and GUM, respectively, and 1.52% for the conventional paddy (CUN). The annual soil carbon sequestration intensity under GCRPS was estimated to be an average of −1.33 Mg C ha−1 yr−1, which is approximately 44% higher than the conventional paddy. The annual NEGE were 10.80–11.02 Mg CO2-eq ha−1 yr−1 for the conventional paddy and 3.05–9.37 Mg CO2-eq ha−1 yr−1 for the GCRPS, suggesting the potential feasibility of GCRPS in reducing net greenhouse effect from rice cultivation. Using organic fertilizers for GCRPS considerably reduced annual emissions of CH4 and N2O and increased soil carbon sequestration, resulting in the lowest NEGE (3.05–5.00 Mg CO2-eq ha−1 yr−1). Accordingly, water-saving GCRPS with organic fertilizer amendments was considered the most promising management regime for simultaneously achieving relatively high grain yield and reduced net greenhouse gas emission.

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Hoylaerts, M. F., T. Manes, and J. L. Millán. "Allelic Amino Acid Substitutions Affect the Conformation and Immunoreactivity of Germ-Cell Alkaline Phosphatase Phenotypes." Clinical Chemistry 38, no. 12 (December 1, 1992): 2493–500. http://dx.doi.org/10.1093/clinchem/38.12.2493.

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Abstract The gene encoding placental alkaline phosphatase (PLAP) displays a well-documented allelic polymorphism. Likewise, different phenotypes exist for the PLAP-related germ-cell alkaline phosphatase (GCAP). We investigated the extent to which various allelic GCAP positions are critical in determining the enzymatic, structural, and immunological properties of GCAP phenotypes. Three homozygous GCAP phenotypes [JEG3, BeWo, and wild-type (wt) GCAP] were analyzed and compared with a "core" GCAP mutant that contains the seven amino acid substitutions that are consistently different between PLAP and GCAP but are common to the three known allelic GCAP genotypes. Although some substitutions could influence the electrophoretic behavior of the phenotypes, the allelic differences did not affect the kinetic properties of GCAP. However, they did affect the immunoreactivity and conformation of the variants as detected with a panel of 18 epitope-mapped monoclonal antibodies (MAbs) to PLAP. The selective immunoreactivity of the PLAP/GCAP-discriminating MAb C2 was critically dependent on the nature of the allelic residues 133 and 361 in GCAP. Residue 133 was also important for the general stability of the molecule because BeWo and wt GCAP, which have Asn133 and Val133, respectively, instead of Met133, showed a consistently reduced heat stability compared to core GCAP and JEG3. Because the core GCAP mutant consistently shows the characteristics of wt GCAP, its use as an antigen should allow the generation of monoclonal antibodies to GCAP that will not cross-react with PLAP and whose immunoreactivity will only marginally be influenced by allelic GCAP variation.

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Liu, M., M. Dannenmann, S. Lin, G. Saiz, G. Yan, Z. Yao, D. Pelster, et al. "Ground cover rice production system facilitates soil carbon and nitrogen stocks at regional scale." Biogeosciences Discussions 12, no. 4 (February 27, 2015): 3647–74. http://dx.doi.org/10.5194/bgd-12-3647-2015.

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Abstract. Rice production is increasingly challenged by irrigation water scarcity, however covering paddy rice soils with films (ground cover rice production system: GCRPS) can significantly reduce water demand as well as overcome temperature limitations at the beginning of the vegetation period resulting in increased grain yields in colder regions of rice production with seasonal water shortages. It has been speculated that the increased soil aeration and temperature under GCRPS may result in losses of soil organic carbon and nitrogen stocks. Here we report on a regional scale experiment, conducted by sampling paired adjacent Paddy and GCRPS fields at 49 representative sites in the Shiyan region, which is typical for many mountainous areas across China. Parameters evaluated included soil C and N stocks, soil physical and chemical properties, potential carbon mineralization rates, fractions of soil organic carbon and stable carbon isotopic composition of plant leaves. Furthermore, root biomass was quantified at maximum tillering stage at one of our paired sites. Against expectations the study showed that: (1) GCRPS significantly increased soil organic C and N stocks 5–20 years following conversion of production systems, (2) there were no differences between GCRPS and Paddy in soil physical and chemical properties for the various soil depths with the exception of soil bulk density, (3) GCRPS had lower mineralization potential for soil organic C compared with Paddy over the incubation period, (4) GCRPS showed lower δ15N in the soils and plant leafs indicating less NH3 volatilization in GCRPS than in Paddy; and (5) GCRPS increased yields and root biomass in all soil layers down to 40 cm depth. Our results suggest that GCRPS is an innovative rice production technique that not only increases yields using less irrigation water, but that it also is environmentally beneficial due to increased soil C and N stocks at regional scale.

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Steinacker, Reinhold. "A New Look to the Generalized CAPE." Journal of the Atmospheric Sciences 74, no. 3 (March 1, 2017): 767–81. http://dx.doi.org/10.1175/jas-d-15-0210.1.

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Abstract A determination of the generalized CAPE (GCAPE) is suggested where instead of an adiabatic reversible vertical redistribution of air in a conditionally unstable atmosphere, irreversible processes with regard to the water cycle are taken into account. Irreversible processes like entrainment or atmospheric dissipation due to precipitation generally reduce the generation of kinetic energy. Irreversible pseudoadiabatic processes, in contrast, increase the availability of convective potential energy considerably. It is further increased significantly when an irreversible redistribution of water in the atmosphere due to precipitation and its corresponding evaporation is considered. Finally, the contributions of the ice phase in clouds and solid precipitation evaporation to GCAPE are investigated. The second aim of this paper is to compare CAPE and GCAPE in an unstable atmosphere. As an important result, it is shown that CAPE and GCAPE are inequivalent metrics of stability. It is even possible that an atmospheric profile with a considerable GCAPE shows a zero CAPE value. With the aid of different models with increasing complexity of thermodynamic processes, comparisons of numerical values of CAPE and GCAPE for an idealized and a real atmospheric profile are carried out. Although the mechanism and fraction of realization of convective available potential energy may be very different in individual weather systems, the pseudoadiabatic GCAPE arguably seems to be the better quantity than CAPE to compare or calibrate energy conversions in the atmosphere during organized deep convection with precipitation, because convection requires GCAPE but not necessarily CAPE. Evaluations have shown that on all days with thunderstorms in Vienna during a 9-yr period, GCAPE was positive, while a considerable fraction of these days showed zero CAPE.

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Satoh, Tatsunori, Masataka Kikuyama, Keiko Sasaki, Hirotoshi Ishiwatari, Shinya Kawaguchi, Junya Sato, Junichi Kaneko, and Hiroyuki Matsubayashi. "Detectability on Plain CT Is an Effective Discriminator between Carcinoma and Benign Disorder for a Polyp >10 mm in the Gallbladder." Diagnostics 11, no. 3 (February 25, 2021): 388. http://dx.doi.org/10.3390/diagnostics11030388.

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An appropriate diagnosis is required to avoid unnecessary surgery for gallbladder cholesterol polyps (GChPs) and to appropriately treat pedunculated gallbladder carcinomas (GCs). Generally, polyps >10 mm are regarded as surgical candidates. We retrospectively evaluated plain and contrast-enhanced (CE) computed tomography (CT) findings and histopathological features of 11 early GCs and 10 GChPs sized 10–30 mm to differentiate between GC and GChP >10 mm and determine their histopathological background. Patient characteristics, including polyp size, did not significantly differ between groups. All GCs and GChPs were detected on CE-CT; GCs were detected more often than GChPs on plain CT (73% vs. 9%; p < 0.01). Sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy for GCs were 73%, 90%, 89%, 75%, and 81%, respectively. On multivariate analysis, lesion detectability on plain CT was independently associated with GCs (odds ratio, 27.1; p = 0.044). Histopathologically, GChPs consisted of adipose tissue. Although larger vessel areas in GCs than in GChPs was not significant (52,737 μm2 vs. 31,906 μm2; p = 0.51), cell densities were significantly greater in GCs (0.015/μm2 vs. 0.0080/μm2; p < 0.01). Among GPs larger than 10 mm, plain CT could contribute to differentiating GCs from GChPs.

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Liu, M., M. Dannenmann, S. Lin, G. Saiz, G. Yan, Z. Yao, D. E. Pelster, et al. "Ground cover rice production systems increase soil carbon and nitrogen stocks at regional scale." Biogeosciences 12, no. 15 (August 14, 2015): 4831–40. http://dx.doi.org/10.5194/bg-12-4831-2015.

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Abstract. Rice production is increasingly limited by water scarcity. Covering paddy rice soils with films (so-called ground cover rice production system: GCRPS) can significantly reduce water demand as well as overcome temperature limitations at the beginning of the growing season, which results in greater grain yields in relatively cold regions and also in those suffering from seasonal water shortages. However, it has been speculated that both increased soil aeration and temperature under GCRPS result in lower soil organic carbon and nitrogen stocks. Here we report on a regional-scale experiment conducted in Shiyan, a typical rice-producing mountainous area of China. We sampled paired adjacent paddy and GCRPS fields at 49 representative sites. Measured parameters included soil carbon (C) and nitrogen (N) stocks (to 1 m depth), soil physical and chemical properties, δ15N composition of plants and soils, potential C mineralization rates, and soil organic carbon (SOC) fractions at all sampling sites. Root biomass was also quantified at one intensively monitored site. The study showed that: (1) GCRPS increased SOC and N stocks 5–20 years following conversion from traditional paddy systems; (2) there were no differences between GCRPS and paddy systems in soil physical and chemical properties for the various soil depths, with the exception of soil bulk density; (3) GCRPS increased above-ground and root biomass in all soil layers down to a 40 cm depth; (4) δ15N values were lower in soils and plant leaves indicating lower NH3 volatilization losses from GCRPS than in paddy systems; and (5) GCRPS had lower C mineralization potential than that observed in paddy systems over a 200-day incubation period. Our results suggest that GCRPS is an innovative production technique that not only increases rice yields using less irrigation water, but that it also increases SOC and N stocks.

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Muto, Akira, Junichi Nakai, and Koichi Kawakami. "Brain Imaging with Improved GCaMPs in Zebrafish." Neuroscience Research 68 (January 2010): e65. http://dx.doi.org/10.1016/j.neures.2010.07.053.

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Tshwenya, Luthando, and Omotayo A. Arotiba. "Ethylenediamine functionalized carbon nanoparticles: synthesis, characterization, and evaluation for cadmium removal from water." RSC Advances 7, no. 54 (2017): 34226–35. http://dx.doi.org/10.1039/c7ra04709f.

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Stavropoulou, G., G. Tzovla, and A. Georgopoulos. "Can 3D Point Clouds Replace GCPs?" ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences II-5 (May 28, 2014): 347–54. http://dx.doi.org/10.5194/isprsannals-ii-5-347-2014.

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Over the past decade, large-scale photogrammetric products have been extensively used for the geometric documentation of cultural heritage monuments, as they combine metric information with the qualities of an image document. Additionally, the rising technology of terrestrial laser scanning has enabled the easier and faster production of accurate digital surface models (DSM), which have in turn contributed to the documentation of heavily textured monuments. However, due to the required accuracy of control points, the photogrammetric methods are always applied in combination with surveying measurements and hence are dependent on them. Along this line of thought, this paper explores the possibility of limiting the surveying measurements and the field work necessary for the production of large-scale photogrammetric products and proposes an alternative method on the basis of which the necessary control points instead of being measured with surveying procedures are chosen from a dense and accurate point cloud. Using this point cloud also as a surface model, the only field work necessary is the scanning of the object and image acquisition, which need not be subject to strict planning. To evaluate the proposed method an algorithm and the complementary interface were produced that allow the parallel manipulation of 3D point clouds and images and through which single image procedures take place. The paper concludes by presenting the results of a case study in the ancient temple of Hephaestus in Athens and by providing a set of guidelines for implementing effectively the method.

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Bonì, Francesco, Valerio Marino, Carlo Bidoia, Eloise Mastrangelo, Alberto Barbiroli, Daniele Dell’Orco, and Mario Milani. "Modulation of Guanylate Cyclase Activating Protein 1 (GCAP1) Dimeric Assembly by Ca2+ or Mg2+: Hints to Understand Protein Activity." Biomolecules 10, no. 10 (October 5, 2020): 1408. http://dx.doi.org/10.3390/biom10101408.

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The guanylyl cyclase-activating protein 1, GCAP1, activates or inhibits retinal guanylyl cyclase (retGC) depending on cellular Ca2+ concentrations. Several point mutations of GCAP1 have been associated with impaired calcium sensitivity that eventually triggers progressive retinal degeneration. In this work, we demonstrate that the recombinant human protein presents a highly dynamic monomer-dimer equilibrium, whose dissociation constant is influenced by salt concentration and, more importantly, by protein binding to Ca2+ or Mg2+. Based on small-angle X-ray scattering data, protein-protein docking, and molecular dynamics simulations we propose two novel three-dimensional models of Ca2+-bound GCAP1 dimer. The different propensity of human GCAP1 to dimerize suggests structural differences induced by cation binding potentially involved in the regulation of retGC activity.

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Song, Ying, Jian-Gang Wang, Rui-Fang Li, Yan Li, Zhao-Chu Cui, Leng-Xin Duan, and Fei Lu. "Gecko Crude Peptides Induce Apoptosis in Human Liver Carcinoma CellsIn Vitroand Exert Antitumor Activity in a Mouse Ascites H22 Xenograft Model." Journal of Biomedicine and Biotechnology 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/743573.

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Aim. To investigate the anti-tumor effects and mechanisms of gecko crude peptides (GCPs)in vitroandin vivo.Methods. 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay was applied to measure the effects of GCPs on the HepG2 cell viability. Fluorescence morphology was used to identify apoptotic cells. A xenograft H22 liver cancer model was established in Kunming mice. The tumor-bearing mice were treated with daily intraperitoneal injections of normal saline (NS group) or GCPs (80, 40 or 20 mg/kg) for 10 days, or once per two days with 2 mg/kg doxorubicin (ADR group;n=10each). Serum tumor necrosis factor (TNF-α) and interleukin (IL)-6 were quantified using ELISA assay.Results. GCPs significantly inhibited the growth of HepG2 cells and induced typical apoptotic morphological features through increasing bcl-2/bax ratio in a dose- and time-dependent mannerin vitro. The tumor weights of the ADR group, GCPs (H) group, GCPs (M) group, GCPs (L) group were smaller compared to the NS group. While the white blood cell count, thymus index, spleen index were higher in the high dose GCPs group than the NS group (P<0.05), the VEGF expression in tumor tissue and serum TNF-αand IL-6 levels in the GCPs groups were lower than the NS group (P<0.05).

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DONG, Fei-fei, Li-na AN, Guo-kun WANG, and Yong-wen QIN. "GCaMPs: promising tools for in vivo calcium imaging." Academic Journal of Second Military Medical University 33, no. 1 (December 4, 2013): 83–87. http://dx.doi.org/10.3724/sp.j.1008.2013.00083.

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Journal articles on the topic 'GCAPs'

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